Telephone instrument



(No Model.) y

J. E. KEELYN.

TELEPHONE INSTRUMENT. f

No. 581,350. l Patented Apr. 27, 1897.

Wze 6,5.

Nrrn rares JAMES E. KEELYN, OF CHICAGO, ILLINOIS.

TELEPHONE INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 581,350, dated April27, 1897.

Serial No. 618,090. (No model.)

To all whom t may concern:

Be it known that I, JAMES E. KEELYN, a citizen of the United States,residing at Ohicago, in the county of Cook and State of Il1inois, haveinvented a new and useful Im provement in Telephone Instruments, ofwhich the following is a specification.

The object of my invention is to produce a telephone instrument of fewand simple parts which will be efficient and d urable and at the sametime possess means whereby the magnets maybe readily adjusted toward andfrom the diaphragm.

For a detailed description of my invention reference is made to theaccompanying drawings, which form a part of this specification, and inwhich- Figure l is a sectional View of a complete instrument. Fig. 2 isa side elevation of the bar-magnets and coils, and Fig. 3 is aperspective view of an adj ustment-block.

Like letters refer to the same parts throughout the drawings andspecification.

A is the outer shell, and B the mouthpiece. These two parts screwtogether and clamp the diaphragm D between them in the ordinary manner.

F F are bar-magnets arran ged,preferably, in pairs. These pairs are heldapart at one end by the block II of hard rubber or other suitablenon-niagnetic material and at the other end by the block I of soft iron.On each side of the block II and between it and the pairs of bar-magnetsare the soft-iron pole-pieces or cores G G. The bar-magnets F F, blocksI-I and I, and the pole-pieces are all firmly clamped together by thescrews .I J. The screw J passes through the hole o in the block II, bothpole-pieces G, and through the barmagnets FF. This screw is of brass orany other suitable non-magnetic material to prevent the short-circuitingof the magnetic lines. The screw J', at the other end of the magnets, ispreferably of iron.

The segmental block H, which is substantially of the form shown in Fig.3, is screwthreaded on its largest circumference, so as to engage athread g on the inner surface of the shell A.

On the pole-pieces G are slipped the coils K K, which are securelyclamped in place by any suitable means. A tailpiece L, of hard rubber orothersuitable material, is so shouldered as to fit in the end of thereceiver-shell. Lugs on the inner periphery of the receiver shell andcorresponding depression on the tailpiece serve to keep the latter fromturning in its place.

A screw O, exteudingthrough the tailpiece and engaging in a tapped holein the block I, serves to clamp the magnets firmly in any position towhich they have been adjusted and also to hold the tailpiece in place.When it is desired to adjust the magnets to a position closer to orfarther from the diaphragm, the screw O is taken out and the bar-magnetsturned in one direction or the other. This turns the block II in thescrew-threaded portionof the shell A, thus moving the magnetslongitudinally with respect to the shell. The screw O is then replacedand the en tire mechanism is firmly bound together.

To the binding-posts R R on the tailpiece are soldered heavy leading-inwires w w. These run each through a hole 7L and are firmly knotted, asat 7s, to prevent their being withdrawn through the block. The finewires with which the magnets are wound are then soldered to the ends ofthe heavy leading-in wires, thus rendering the connections complete. Theknotting of the leading-in wires prevents any strain ever coming on thesmall magnet-wires when the tailpiece is removed. Sufficient slack isleft in the leading-in wires to allow the removal of the tailpiece ashort distance to give access to the end of the magnets for purposes ofadjustment.

It is found that in receiving instruments of the ordinary type muchtrouble is experienced in keeping the adjustment permanent. This is dueto the fact that the magnet is rigidly secured to the receiver-shell ata point at a considerable distance from the diaphragm. As steel and hardrubber differ very widely as to their coefficients of expansion underchange of temperature, it follows that with every change of temperaturethe distance between the diaphragm and the pole-pieces is altered, owingto the unequal expansion or contraction of steel and hard rubber. Asudden change in temperature will thus often make an instrumentinoperative. By my improvement this trouble is almost entirely obviated,as the point at which the magnets are secured to the shell is so closeto the diaphragm that the difference in expansion between the hardrubber and the steel cannot be noticed.

I do not desire to limit myself to the use of a compound bar-magnet norto the exact speeiiic construction herein shown and described; but

That I claim as new, and desire to secure by Letters Patent, is-

l. In a telephone instrument, a magnet carrying a coil at one end, adisk screw-threaded on its outer surface rigidly mounted on said magnet,and an outer shell carrying a diaphragm and having on its inner surfacea Screwethread into which said threaded disk fits, whereby the magnetmay be adjusted longitudinally toward or from the diaphragm by turningit in thershell, and means whereby the magnet may be clamped into anydesired position, substantially as described.

2. In a telephone instrument, a bar-magnet carrying a coil at one end, adisk screwthreaded on its outer surface and rigidly mounted on saidmagnet in proximity to said coil, an outer shell having on itsinnersurface a screw-thread into which said threaded disk fits, a tailpieceand a screw passing through said tailpiece and engaging the end of thebar-magnet, thus serving to bind the tailpiece, the bar-magnet and theouter shell rigidly together, substantially as described.

In a telephone-receiver, an outer shell and an ear-piece, carrying adiaphragm be tween them, a bar-magnet carrying a coil at one end, acircular disk screw-threaded on its outer surface and mounted on saidmagnet, a screw-thread on the inner surface of said outer shell at theend near the diaphragm, into which the screw-threaded circular disktits, a tailpiece carrying binding-posts and leading-in wires, and ascrew passing through said tailpiece and engaging the end of thebar-magnet, thereby binding the magnets in any position to which theyhave been adjusted and at the same time holding the tailpiece' in place,substantially as described.

4. In a telephone-receiver, an outer shell andan ear-piece, a diaphragmclamped between them, two laminated bar-magnets, a screw-threadedadjustlnentblock of hard rubber or like material clamped between theends of said bar-magnets nearest the diaphragm, ablock of sott ironclamped between the other ends of said bar-magnets, a screwthread on theinner surface of said outer shell into which said adjustment-block tits,soft-iron pole-pieces, each carrying a bobbin clamped on each side ofthe adj ustmentblock and between it and the magnet-bars, a tailpieeeshouldered to fit in the end of the outer shell, and a screw passingthrough said tailpiece, and engaging a tapped hole in Said block of softiron, thus serving to clamp the magnets in any desired position and atthe same time secure the tailpiecc rml y in place, substantially asdescribed.

JAMES E. KEELYN.

Witnesses:

K. B. MILLER, S. S. SToU'r.

